Basically, whether you like UV filters or not, filters will degrade image quality. The extent of this degradation depends on how good of a filter you buy. I'm with the camp that uses UV filters, but I will admit that I'm sacrificing image quality.
If you use a cheapo Tiffen filter, you could see some loss, but if you stick to a high end filter like B+W F-Pro or Hoya HD or Helipan's high end ones, you should be fine.
The purpose of the filter is usually to protect against scratches or to complete the weather seal of the lens (i.e. Canon's L-lenses), or to just add as a protection layer in general (like kids with greasy fingers). It's not really to protect your sensor from UV rays, although I think there is some (very little) benefit that's not really noticeable.
So yeah I'd recommend sites like: 2filter.net to find yourself a good filter. I use Hoya HD and B+W F-Pro for my lenses. I know they're a tad expensive, but if you want to go slightly cheaper Hoya HMC or Pro1s are fine. Just make sure you get multi coated filters, and the uncoated stuff = junk. Tiffen = junk.
Facebook
Twitter